The subject matter disclosed herein relates to X-ray tube radiation sources and more particularly to the processing of X-ray tubes.
In non-invasive imaging systems, X-ray tubes are used in projection X-rays systems, fluoroscopy systems, tomosynthesis systems, and computer tomography (CT) systems as a source of X-ray radiation. Typically, the X-ray tube includes a cathode and an anode. An emitter within the cathode emits a stream of electrons in response to heat resulting from an applied electrical current via the thermionic effect. The anode includes a target that is impacted by the stream of electrons. The target, as a result, produces X-ray radiation and heat. Such systems are useful in medical contexts, but also for parcel and package screening, part inspection, various research contexts, and so forth.
The radiation traverses a subject of interest, such as a human patient, and a portion of the radiation impacts a detector or photographic plate where the image data is collected. In some X-ray systems, the photographic plate is then developed to produce an image which may be used by a radiologist or attending physician for diagnostic purposes. In digital X-ray systems, a photo detector produces signals representative of the amount or intensity of radiation impacting discrete pixel regions of a detector surface. The signals may then be processed to generate an image that may be displayed for review. In CT and tomosynthesis systems, a detector array, including a series of detector elements, produces similar signals through various positions as a gantry is displaced around a patient, and processing techniques are used to reconstruct a useful image of the subject.
The X-ray tube may have a useful life over a large number of examination sequences, and must generally be available for examination sequences upon demand in a medical care or other facility. Given the demanding schedules to which X-ray tubes are often subjected, failure of the tubes is of particular concern. Various failure modes have been observed in X-ray tubes, and these have a variety of sources. For example, during processing of the X-ray tube moisture, hydrocarbons, or other particulates may remain within the X-ray tube even after bakeout heating and processing under vacuum. Further sources of X-ray tube failure occur during post-processing use due to leaks, degradation in the cathode or anode materials, and so forth, where particulates may be created or freed within the tube. These particulates may result in eventual failure of the tubes over time.